Operating vehicles in inclement weather is difficult and many devices have been developed to aid drivers. For example, cars and trucks (not to mention boats, airplanes and trains) have windshield wipers to clear rainwater, snow and other forms of precipitation off of the windshield. Today, many vehicles also have wipers mounted for use on the rear window and mounted for use on headlights. However, wipers for outside rearview mirrors have not become popular even though the safety features of such devices are self-evident. This is because the prior art devices are not without problems of their own.
For example U.S. Pat. No. 6,324,718 to Johnson discloses a side mounted wiper assembly for external rearview mirrors. This device has two major problems. First, the mechanism responsible for moving the wiper across the mirror glass is exposed to the elements. Because of this, the mechanism is prone to corrosion and, in the event of a freezing rain or heavy snow, can become inoperative. Additionally, the wiper is only secured or mounted on one end. Where such an arrangement may be necessary for windshield wipers it is a disadvantage for wipers on rearview mirrors. When driving, air currents push windshield wipers against the glass helping the wipers to maintain contact with the glass. However, air currents moving around the mirror, especially at speeds necessary for highway travel, can act to lift the wiper off of the mirror glass. The result is that the wiping action by the wiper is less effective or ineffective when it is needed most leaving, for example, streaks that interfere with visualizing objects with the rearview mirror.
U.S. Pat. No. 6,546,590 to Waters discloses a clamp-on wiper assembly for truck rearview mirrors. This device has several problems. First, the wiper, while being attached on both sides, runs up a partially exposed track on small wheels. This design does not prevent the device from freezing since much of the mechanism is exposed to the elements. Another problem with the device is that the wiper is moved via an extending telescopic arm that is attached to only one side of the wiper blade. Such a design is inherently flawed since the trailing end of the wiper blade as well as the wiper itself creates a drag on the system. This drag results in 1) a burden on the motor and drive system leading to damage of the system and/or premature failure and 12) the uneven cleaning of the mirror glass.
U.S. Pat. No. 7,069,617 to James discloses a pneumatic wiper system for rearview mirrors. This system is design to be spliced into and powered by the truck's pneumatic air source used for the truck's air brake system. The wiper is moved across the mirror glass in a motion that is horizontal to the ground. The wiper is mounted in the middle of the blade. Because of the natural and necessary flexibility of the wiper blade (being made out of a natural or synthetic rubber) the blade and is susceptible to vibration and motion caused by air currents resulting from vehicle movement. This problem results in the less effective or ineffective cleaning of the mirror glass. Additionally, the pneumatic system operates a push rod to which the wiper is attached. This push rod is susceptible to being rendered inoperable in icy conditions.
U.S. Pat. No. 3,685,081 to Pittman discloses a rearview mirror wiper mechanism but suffers from the design flaw of the wiper being supported on one end only and, thus, is susceptible to wind conditions caused during driving, as are the systems above It also utilizes a complicated and expensive to manufacture double track mechanism within the mirror housing to maintain the blade's horizontal position during use.
U.S. Pat. No. 3,866,258 to DeGraw discloses a rearview wiper mechanism that suffers from having a large number of moving parts exposed to the elements. This design is subject to freezing solid when exposed to freezing rain or sleet and snow, especially when the vehicle is parked for any length of time. Because of the plethora of moving parts exposed to the weather, the device would be difficult to clean of ice without damaging the mechanisms.
U.S. Pat. No. 3,855,661 to Prince discloses a rearview wiper mechanism that also suffers from 1) exposed moving parts and 2) the wiper blade only being supported at one location. Thus, this device is also prone to problems caused by icing and wind current causing havoc with the blade leading to uneven cleaning of the mirror surface.
U.S. Pat. No. 3,940,822 to Emerick and Davis discloses a wiper device for rearview mirrors that causing the wiper blade to rotate or spin over a limited portion of the mirror. Since a rearview mirror is typically rectangular, this rotating wiper blade design can only clean a small portion of the overall surface area of the mirror leaving a large portion of the mirror uncleaned. Also, this design requires a hole be drilled in the mirror glass so the wiper can be mounted and powered
U.S. Pat. No. 3,968,537 to Wagenhofer discloses a rearview mirror wiper device. This device suffers from the problem of having the wiper blade supported only on one end of the blade. This design cannot ensure that the blade receives even pressure along the entire length of the blade thus resulting in uneven cleaning of the mirror glass.
U.S. Pat. No. 5,353,466 to Smith, et al., discloses a rearview mirror wiper mechanism that is driven by a complicated system of cables, pulleys and gears. Inherent problems in this device are the loosening and stretching of the cables, cables running off of the pulleys and cables breaking. Additionally, this device is difficult and expensive to manufacture and difficult to maintain to ensure optimal performance.
Thus, what is needed is a rearview wiper system that ensures even and adjustable pressure over the entire surface of the wiper blade for optimal cleaning of the mirror glass, has a minimum of parts exposed to the elements and is easy for the user to maintain.